Statement of problem: By decreasing the proportion of filler, flowable composites are easy to adapt to small cavity preparations. However, the wear resistance of flowable composites is a clinical concern, as improved wear has been related to increased filler percentage.
Purpose: The purpose of this study was to compare wear for flowable composites and comparable heavily filled materials.
Material and methods: Wear by attrition and abrasion (microm) of microfilled flowable (Heliomolar Flow) and heavily filled microfill (Heliomolar HB) was measured and compared to a microhybrid flowable (Tetric Flow) and a heavily filled microhybrid (Tetric HB). There were 5 specimens, 2 mm thick and 15 mm in diameter, in each group. The Oregon Health Sciences University oral wear simulator was used to produce abrasive wear and attrition for all specimens. Abrasion and attrition of the substrates were measured using a profilometer. Data were subjected to a 3-way analysis of variance for the 3 main factors: composite type, filler load, and wear type (alpha=.05)
Results: Composite wear rates were significantly influenced (P <.01) by both the type of wear and the filler amount. Abrasive wear occurred less than wear by attrition, and the heavily filled composites experienced less wear than the flowable composites.
Conclusions: Results of this in vitro study suggest that highly filled microhybrid composites may have greater wear resistance for contact-supporting posterior restorations. However, in small noncontact restorations where longevity may be dictated by abrasion, flowable microfilled resins may be adequate.